The Sheath Defined
The sheath is a species of culotte in which elasticized fabric is stretched across the front of the crotch of an otherwise legless, panty-cut brief (SS4120). The sheath combines modesty, in that the cloth covering crotch is apparently obscured, with revelation, because in fact the crotch can be viewed if the angle is right (MM4501, MM4720).
The sheath, it is important to note, is skirted on only the front-side. In the early 1940s sheath waistlines remain high (SS4110, MS4310), often with drawstrings or belts, and leglines vary from well below crotch (PG194110) to about level with it (MM4701, VLAKE). Legs, even with competition from stomach, remain an important erogenous zone.
By modern standards, the sheath is a complicated garment. Constructed of no less than ten different pieces, it incorporates elastic, lining, panels and a zipper closure (fig. 13-3a, pattern).
Why Sheath Evolved
The sheath is morphogenicized from the skirted panty during the early 1940s when the skirt in the rear is shed, The resulting backside is covered but unskirted, so the buttocks come more into play, especially when a dart between them insures a deeper fit and allows a more discriminating view of the elasticity shaped hips (Grable).
Sheaths & Soutien-gorge
The sheath is most often comboed with the shelf bra (BM4110) or shelf halter (PG4110, SS4110, SS4130, SS4140, MS4310) to form a basic silhouette. This silhouette is among the most stable and long-lasting in swimsuit history, and lasts through the 1940s and into the 1950s until the smaller and more revealing bikini finally force it aside.
The End of Its Life Cycle
The sheath continues to be worn throughout the 1940s, long after the invention of the bikini and long past its prime (LM48G5, DW4910, PC5010). This is a statement about the cycle of fashion, and it shows how an idea, one implanted into the culture, can continue to have play even when newer ideas are replacing it.
The defining characteristic of the sheath is a tight skirt of fabric in the front of the crotch.